Passive Laser Listening Countermeasure using antireflection materials

In this research, laser listening countermeasure using absorbing layers deposited on surface of glass, which is located infront of the sound source was investigated experimentally. To do this, samples with one, two and three-layers of Al2O3, TiO2, MgF2, have made and used. Deposition performed by evaporation technique on BK7 glass substrate using electron gune beam. During the deposition, the optical thickness was controlled by the thickness monitoring system.Reflectance of gayers and relative intensity of the reflected beam from the coated glass surface were measured due to investigation of the effect of anti-reflective layers. Using the TFD Scope simulation software the sound graph was evaluated too.The results showed that at 632.8 nm laser wavelength, the sample coated by three layers of Al2O3 and TiO2, MgF2 significantly reduces the reflection of the laser beam to less than one percent.